1. Field of the Invention
The present invention relates to a surface mount light emitting diode assembly and a backlight module using the surface mount light emitting diode assembly, and more particularly to a surface mount light emitting diode assembly having a high light emitting efficiency.
2. Description of Related Art
Light emitting diode (LED) has many advantages, such as high luminance, low power consumption, good matching with integrated circuit, long-term reliability and environment friendliness. LED has been widely used as backlight source in liquid crystal display (LCD), as described in an article entitled “Sequential Color LED Backlight Driving System for LCD Panels” cited in a publication of IEEE Transactions on power electronics, Vol. 22, No. 3 May 2007, authored by Chien-Chih Chen.
A backlight source using LED normally includes a light guiding plate having a light incidence surface and a plurality of surface mount LEDs disposed adjacent to the light incidence surface. Each of the surface mount LEDs includes a substrate, an LED chip on the substrate and a lens package arranged on the substrate for covering the LED chip. The lens package has a light emitting surface away from the substrate. Normally, the light emitting surface is a plane surface. Light rays emitted by the LED chip transmit to ambient air through the light emitting surface. As a refractive index of the lens package is larger than that of the ambient air, the light rays pass from an optically denser medium to an optically thinner medium when transmitted from the lens package to the ambient air through the light emitting surface. Accordingly, a total reflection of the light rays tends to occur so that part of the light rays can not reach the outside of the lens package to cause light energy loss of the surface mount LED assembly.
Accordingly, what is needed is a surface mount LED assembly which can reduce light energy loss.